Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Operating activities:
Net income	$ 379,507		$ 331,456
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and intangibles	95,004		89,682
Amortization of debt discount and issuance costs	1,041		1,000
Excess tax benefit from stock options exercised	(23,849)		(18,681)
Deferred income taxes	(12,686)		(80)
Share-based compensation programs	12,137		11,174
Other	2,718		3,117
Changes in operating assets and liabilities:
Accounts receivable	(28,422)		(56,681)
Inventory	(87,734)		(69,046)
Accounts payable	245,761		129,747
Income taxes payable	39,412		23,823
Other	32,636		(6,099)
Net cash provided by operating activities	655,525		439,412
Investing activities:
Purchases of property and equipment	(194,929)		(176,577)
Proceeds from sale of property and equipment	789		678
Payments received on notes receivable	1,835		2,166
Net cash used in investing activities	(192,305)		(173,733)
Financing activities:
Proceeds from the issuance of long-term debt	0		299,976
Payments of debt issuance costs	0		(1,879)
Principal payments on capital leases	(36)		(189)
Repurchases of common stock	(299,655)		(501,914)
Excess tax benefit from stock options exercised	23,849		18,681
Net proceeds from issuance of common stock	34,735		37,448
Net cash used in financing activities	(241,107)		(147,877)
Net increase in cash and cash equivalents	222,113		117,802
Cash and cash equivalents at beginning of the period	231,318	[1]	248,128
Cash and cash equivalents at end of the period	453,431		365,930
Supplemental disclosures of cash flow information:
Income taxes paid	189,944		170,100
Interest paid, net of capitalized interest	$ 25,190		$ 21,706

[1] The balance sheet at December 31, 2013, has been derived from the audited consolidated financial statements at that date, but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.